Toshiba and TEPCO Advance SF₆-Free 300 kV GIS Technology with Natural-Origin Gases
The transition toward SF₆-free high-voltage equipment is gaining momentum as the power industry looks for more environmentally sustainable alternatives to sulfur hexafluoride (SF₆).
Toshiba has announced that its 300 kV gas circuit breaker (GCB) and three-phase gas-insulated busbar (GIB) using only naturally sourced gases have been selected by TEPCO Power Grid in Japan. According to Toshiba, this represents the world’s first adoption of these two products at this voltage level.
The formal order contract is expected to follow, with delivery of the 300 kV GCB planned for fiscal year 2029 and the GIB for fiscal year 2030.
Why Is the Industry Moving Away from SF₆?
SF₆ has been widely used in high-voltage electrical equipment because of its excellent dielectric insulation and arc-extinguishing properties. It has played an important role in gas-insulated switchgear (GIS), gas circuit breakers and other transmission and distribution equipment for decades.
However, SF₆ is also a very potent greenhouse gas. Its global warming potential is approximately 25,000 times that of CO₂ over a 100-year period, making SF₆ emissions an important environmental concern.
As electrical grids expand and utilities upgrade their high-voltage infrastructure, reducing SF₆ emissions and developing SF₆ replacement technologies have become increasingly important.
Natural-Origin Gases for SF₆-Free High-Voltage Equipment
Toshiba has been developing naturally sourced gas technologies as an alternative approach to conventional SF₆ insulation.
Its AEROXIA™ technology platform is designed for SF₆-free gas-insulated electrical equipment, with a focus on environmental performance, operational practicality and equipment reliability.
The planned deployment of 300 kV GCB and GIB equipment by TEPCO demonstrates that alternative insulation gas technologies are moving beyond laboratory research and pilot projects toward practical applications in high-voltage power networks.
This development is an important indication of the broader direction of the industry: future GIS technology is likely to involve a wider range of insulation gases and gas mixtures rather than relying exclusively on SF₆.
SF₆ Alternatives: From C4F7N to Natural-Origin Gas
Natural-origin gas is not the only pathway being explored for reducing the environmental impact of high-voltage equipment.
Another important development is the use of fluoronitrile-based gas mixtures, particularly C4F7N, in next-generation GIS and medium- and high-voltage electrical equipment.
Compared with conventional SF₆ technology, different alternative gases offer different combinations of dielectric performance, environmental characteristics, operating requirements and equipment compatibility. Therefore, the transition to SF₆ alternatives is not simply a matter of replacing one gas with another.
Gas selection, gas quality control, filling, recovery, vacuum evacuation and gas analysis all become important considerations throughout the equipment lifecycle.
The Importance of Gas Handling in the SF₆ Alternative Era
As the power industry adopts new insulation gases, reliable gas handling systems will remain an essential part of electrical equipment maintenance and commissioning.
For conventional SF₆ equipment, gas recovery, evacuation, filling, filtration, drying and gas quality analysis are already critical operations. With the development of SF₆-free and alternative-gas technologies, equipment manufacturers and service providers will increasingly need flexible systems capable of supporting different gas requirements and application conditions.
At KSTONE, we focus on gas handling and gas analysis technologies for the electrical power industry. Our product portfolio includes SF₆ gas recovery systems, gas analyzers, leak detection equipment, vacuum systems and related gas handling solutions.
At the same time, KSTONE is following the development of C4F7N and other SF₆ alternative technologies, with the goal of supporting the evolving requirements of modern GIS and high-voltage equipment.
A Step Toward a More Sustainable Power Grid
The planned TEPCO deployment of Toshiba’s 300 kV SF₆-free GCB and GIB is more than a single equipment project. It reflects the accelerating transition toward lower-environmental-impact insulation technologies in the transmission and distribution sector.
As utilities and equipment manufacturers continue to evaluate natural-origin gases, C4F7N-based mixtures and other SF₆ alternatives, the requirements for gas quality, gas handling and maintenance will also evolve.
For companies working with GIS and high-voltage equipment, understanding these developments today can help prepare for the next generation of gas-insulated power infrastructure.
KSTONE will continue to follow the development of SF₆ alternative technologies and provide gas handling and gas analysis solutions for the evolving needs of the global power industry.